Characteristics of ever-smokers and never-smokers before propensity score matching
| Ever-smokers | Never-smokers | Standardised difference | |
| N | 190 686 | 370 912 | |
| Index date (days from the origination date) | 1685.0±631.8 | 1662.8±644.2 | 0.035 |
| Male gender | 154 436 (81.0) | 125 704 (33.9) | 1.083 |
| Age | 65.1±13.8 | 66.4±15.3 | −0.086 |
| Patients in hospitals with <500 beds | 113 571 (59.6) | 234 007 (63.1) | – |
| Brinkman Index | 687.1±552.6 | 0 | |
| Target organ of the elective surgery | |||
| Skin or subcutaneous tissues | 27 030 (14.2) | 51 387 (13.9) | |
| Muscle, bone, limb or trunk | 28 735 (15.1) | 77 715 (21.0) | |
| Nervous system, head or CNS | 3837 (2.0) | 8630 (2.3) | |
| Eyes | 5737 (3.0) | 16 015 (4.3) | |
| Ear, nose or throat | 9136 (4.8) | 12 631 (3.4) | |
| Face, mouth or neck | 4214 (2.2) | 8558 (2.3) | |
| Chest | 16 803 (8.8) | 32 501 (8.8) | |
| Cardiovascular | 29 145 (15.3) | 41 977 (11.3) | |
| Abdomen | 61 430 (32.2) | 99 277 (26.8) | |
| Urological system or adrenal gland | 15 084 (7.9) | 21 407 (5.8) | |
| Genital | 18 383 (9.6) | 53 640 (14.5) | |
| Comorbidity | |||
| Heart failure | 26 194 (13.7) | 43 000 (11.6) | −0.064 |
| Coronary artery disease | 33 742 (17.7) | 48 221 (13.0) | −0.131 |
| Peripheral artery disease | 14 275 (7.5) | 19 396 (5.2) | – |
| Myocardial infarction | 5864 (3.1) | 6620 (1.8) | – |
| Stroke/TIA/SE | 15 536 (8.1) | 24 967 (6.7) | – |
| Renal dysfunction | 13 197 (6.9) | 20 416 (5.5) | −0.059 |
| Hepatic dysfunction | 32 266 (16.9) | 51 509 (13.9) | – |
| Hypertension | 76 458 (40.1) | 134 012 (36.1) | −0.082 |
| Diabetes mellitus | 60 156 (31.5) | 95 561 (25.8) | −0.128 |
| Cancer | 105 626 (55.4) | 191 698 (51.7) | −0.074 |
| Infectious disease | 29 603 (15.5) | 48 032 (12.9) | – |
| COPD | 16 370 (8.6) | 14 580 (3.9) | −0.193 |
N (per cent) or mean±SD. Standardised difference was calculated only for variables used for the calculation of propensity score.
CNS, central nervous system; COPD, chronic obstructive pulmonary disease; SE, systemic embolism; TIA, transient ischaemic attack.